The organization of the mammalian sympathetic paravertebral ganglia is complex, and the mechanisms and the degree of central and peripheral integration at this level is not known. The objective of this research is to define the influence of cardiopulmonary neural input to the stellate ganglion (SG) by means of intracellular recordings from single neurons located in the SG of the cat in situ. The input from the cardiopulmonary region to the SG will be produced by a localized stimulation and by applying pressure only in specific chambers of the heart. This information will provide a strong basis for determining if sympathetic reflexes are triggered in part by a peripheral synaptic input. Evidence for this interaction has been supported with preliminary studies by the Principal Investigator. In addition, location of the neurons responsible for this peripheral input will be investigated after the connections to the SG are cut and allowed to degenerate. Furthermore, the sensitivity of the postganglionic neurons in the SG due to a peripheral excitatory input will be studied. Central synaptic input to the SG will be increased by electrical stimulation of the preganglion neurons. Finally, the correlation of the electrophysiology and morphology (including postganglionic projections) will be examined with the use of an iontophoretic injection of horseradish peroxidase. The ultimate goal of this research is to elucidate specific neural influences of the cardiopulmonary sympathetic afferents and preganglionic sympathetic activity on the neural activity of the postganglionic neurons located in the sympathetic ganglia.